Modern tactical aircraft use a number of imaging aids to assist the crew in viewing a scene, selecting targets in the scene, and directing weapons against the selected targets. Visible, infrared, and/or specific spectral bands imaging devices are used in various applications to form an image of the scene. The type imaging spectrum depends upon the mission, weather conditions, the nature of the scene, as well as other factors.
One form of an infrared optical system includes several lenses made of infrared-transparent lens materials. The lenses are arranged at proper positions along an optical path to achieve desired effects by a lens mount assembly. The refractive index and other optical properties of infrared lens materials are strongly dependent on temperature, which impacts the ability of the lens mount assembly to properly position the lens. If the temperature changes so that the optical properties of the lens materials change, the lenses may no longer be properly positioned relative to one another, and the performance of the infrared optical system may be compromised.
Examples of lens mount assemblies can be found in U.S. Pat. Nos. 5,570,238, 7,270,022 and 8,829,416 and U.S. Patent Application Publication No. 2004/0257682 A1.